From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CB687C32792 for ; Mon, 30 Sep 2019 23:22:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9C83320842 for ; Mon, 30 Sep 2019 23:22:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=sifive.com header.i=@sifive.com header.b="Dh/+7RnH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732242AbfI3XWv (ORCPT ); Mon, 30 Sep 2019 19:22:51 -0400 Received: from mail-pf1-f194.google.com ([209.85.210.194]:39077 "EHLO mail-pf1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729224AbfI3XWv (ORCPT ); Mon, 30 Sep 2019 19:22:51 -0400 Received: by mail-pf1-f194.google.com with SMTP id v4so6493984pff.6 for ; Mon, 30 Sep 2019 16:22:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sifive.com; s=google; h=from:to:cc:subject:date:message-id; bh=oD29p9MztJ0+RG65sUk0y34KEPusU0JDw36LEVrb3DM=; b=Dh/+7RnHcSNPu7iFzG4FCn7R4X50q8rBrl/G7Gtjs3SzU9elJmVJzuWimYKVKzvex0 0cAVsUl1VKUbTofnpFFmHlvsWmaIcYDvycKtRt8Hji43hjeBXrQswpYIKQnd7aUtU5MI ur1VGuiON4lQlYpOdff0bLlLBsFqfJPDE6RMW9zuu4EcQikQr8FBDVQgqFvfi0V0M+RQ oZDCjCtTu7LoPjowkun4rJBTH07KC78J3E3N5dUxDyQifXx5rNrg47ifQWJFNrQoB6Ax kqCT0TiyHMr88THW7korngsuFeOx3nCZYM/acKlLsk0rEUMdqtPudIRaA4b4SOS5pw2u nTPw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=oD29p9MztJ0+RG65sUk0y34KEPusU0JDw36LEVrb3DM=; b=TYBxga/X/hPBj+ZqfxlM1/gDS+gygM07BvNCDS9BZJR2iVlWF6GusLJoi3f53i16tV +e/et1LqGzlIaxm18xkQPPRK2+zZaNxRBln8W4tSp4l+NuWnrSOrTBeF36zAyOEjha5j CBJ+8kyH0qU0YpWC9cOfcbg1h5LkOIV3pmfZQoZI1/u7QeiLx1RKVIcvbQSH5Ra5qspk V1A8tPEuugwnSzxlzltU+9ap4J2fLDQDUCTVMpcSAbel8jjBbEH9e3uzLtVL4Tv6wzkk US2Sgh3adJldHj1z4Cv1znAKjF+8V5j02r0LSAcvbngHWI6bdNtF56/KkFgKbxH9qUsw 5Vxw== X-Gm-Message-State: APjAAAXd9ooLE5qT+cDrI6Xxw2X8kUqDGkROpktlO4FZZv1CdPymUZ6i ddM6LJtQxci6A4I6BygTwIWCywGIRy4= X-Google-Smtp-Source: APXvYqxArfBwf2OYAS2ryb5cgYk6T4irZNLwLtqsdIA+0Qk8MxomHoH5QY+tr74ygd6ZBdj4xaOTFQ== X-Received: by 2002:a63:e444:: with SMTP id i4mr27267478pgk.45.1569885770188; Mon, 30 Sep 2019 16:22:50 -0700 (PDT) Received: from nuc7.sifive.com ([12.206.222.5]) by smtp.gmail.com with ESMTPSA id 14sm379629pfn.21.2019.09.30.16.22.48 (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 30 Sep 2019 16:22:49 -0700 (PDT) From: Alan Mikhak X-Google-Original-From: Alan Mikhak < alan.mikhak@sifive.com > To: linux-kernel@vger.kernel.org, martin.petersen@oracle.com, alexios.zavras@intel.com, ming.lei@redhat.com, gregkh@linuxfoundation.org, tglx@linutronix.de, jgg@ziepe.ca, christophe.leroy@c-s.fr, palmer@sifive.com, paul.walmsley@sifive.com Cc: Alan Mikhak Subject: [PATCH] scatterlist: Validate page before calling PageSlab() Date: Mon, 30 Sep 2019 16:22:35 -0700 Message-Id: <1569885755-10947-1-git-send-email-alan.mikhak@sifive.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Alan Mikhak Modify sg_miter_stop() to validate the page pointer before calling PageSlab(). This check prevents a crash that will occur if PageSlab() gets called with a page pointer that is not backed by page struct. A virtual address obtained from ioremap() for a physical address in PCI address space can be assigned to a scatterlist segment using the public scatterlist API as in the following example: my_sg_set_page(struct scatterlist *sg, const void __iomem *ioaddr, size_t iosize) { sg_set_page(sg, virt_to_page(ioaddr), (unsigned int)iosize, offset_in_page(ioaddr)); sg_init_marker(sg, 1); } If the virtual address obtained from ioremap() is not backed by a page struct, virt_to_page() returns an invalid page pointer. However, sg_copy_buffer() can correctly recover the original virtual address. Such addresses can successfully be assigned to scatterlist segments to transfer data across the PCI bus with sg_copy_buffer() if it were not for the crash in PageSlab() when called by sg_miter_stop(). Signed-off-by: Alan Mikhak --- lib/scatterlist.c | 1 + 1 file changed, 1 insertion(+) diff --git a/lib/scatterlist.c b/lib/scatterlist.c index c2cf2c311b7d..f5c61cad40ba 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -807,6 +807,7 @@ void sg_miter_stop(struct sg_mapping_iter *miter) miter->__remaining -= miter->consumed; if ((miter->__flags & SG_MITER_TO_SG) && + pfn_valid(page_to_pfn(miter->page)) && !PageSlab(miter->page)) flush_kernel_dcache_page(miter->page); -- 2.7.4